For the above reasons, reliably and securely handling an otoscope of the art is currently subject to only well trained physicians and not amenable to the larger community of practitioners. A study recently published in the US as a result of a survey has shown that even physicians often fail to (correctly) determine the status of e.g. the subject's eardrum or fail to correctly interpret the image provided by the otoscope (i.e. correct and meaningful object recognition). Such failures result in misinterpretation of the status of the inner ear canal or the eardrum. As a consequence, e.g. over-medication with antibiotics for treating supposed inflammations of the eardrum occurs, because physicians tend to err on the side of caution, or meaningless image interpretation occurs.
Notably, there also exist other otoscopic devices, as e.g. video otoscope, allowing a skilled expert to capture images of the subject's eardrum and the ear canal. Such video otoscopes comprise a bundle of light guides extending from the distal end of the head portion to a CCD-chip located remote from the distal end. The achievable resolution of the images depends on the number of light guides. In order to obtain images having a satisfying resolution, a significant number of individual light guides must be provided rendering devices by far too expensive for routine care. Moreover, all of the known video otoscopes having the CCD-chip located remote from the distal end of the head portion require superior handling skills by he physician. For the above reasons, they are not configured and suitable for domestic use by a larger community of practitioners, nor use by laypersons.
The otoscopic methods known in the art are—as a matter of fact—subject to the structural and geometrical characteristics of otoscopes as described above. All otoscopes currently on the market—including video otoscopes—generally are based on the following fundamental design: a relatively thin open funnel. Length, angle, field of vision and size of the funnels are essentially similar for all marketed otoscopes. As a result of these common characteristics, ease of use (due to safety issues) is limited for such devices. Methods for reliable detection of objects in the ear canal, including the eardrum, are remarkably intricate with such known otoscopes.
Consequently, until today otoscopy has almost exclusively been applied by well-trained medical doctors. However, it would be desirable to extend the capability of otoscopy beyond the trained professionals. Due to its broad spectrum of applications, it should be made amenable to any layperson, such as parents, who may desire to e.g. examine whether dirt or particles is/are located in the children's ear canal.
Prior art document US2013/027515 A1 describes an ear canal side scanner with a small diameter comprising a camera including e.g. a CCD or CMOS chip. The camera can be arranged at a tip of a probe of the side scanner. The scanner allows for side scans of lateral surfaces of the ear canal, e.g. in order to determine the length of the ear canal. The tip of the side scanner is positioned close to the eardrum before scanning.
Prior art document U.S. Pat. No. 5,910,130 A describes an otoscope with a miniature video camera or a solid-state imager, e.g. a CCD or CMOS. A light source can be provided in the form of a continuous ring of light emitting fibres. The head portion of the otoscope has to be introduced far into a straightened ear canal in order to observe the eardrum.
Prior art document US 2011/063428 A1 describes a medical device (an endoscope) comprising illumination means and a video camera based on wafer level optics, e.g. a solid state imager, and having a maximum outer diameter of less than 3.2 mm.
Prior art document US 2009/030295 A1 describes an instrument for capturing an image of an eardrum and a method for locating the eardrum on the image, especially based on color detection or brightness detection. Brightness can be evaluated in order to distinguish between two specific tissues. A rotation mechanism for applying one of two optical filters can be provided.
Prior art document U.S. Pat. No. 7,529,577 B2 describes a method for locating foreign objects in an ear canal, especially by determining the relative content of specific colours within the image using a color sensitive CCD element. Light can be passed from eccentrically arranged light guides via an annular lens on a mirror reflecting the light through a tube of transparent material, and reflected light passes via the mirror through a lens and is captured by a centrally arranged image guide.
Prior art document EP 2 014 220 A1 describes an apparatus for acquiring geometrical data of an ear's cavity with a black and white CCD or a colour sensitive CCD. Thereby, a distance measurement can be carried out, with respect to both a circumferential surface and the eardrum.
Prior art document EP 2 289 391 A1 describes an otoscope with a head portion and a fastening ring for reversibly mounting the head portion to a display portion.
Prior art document EP 2 277 439 A2 describes a clinical ear thermometer including an image sensor which is positioned radially offset, especially in order to provide a cavity in which a temperature sensor can be arranged at a distal end.
It is therefore an object of the present invention to provide a method that allows for reliable identification of objects in the subject's ear and that preferably shall be also domestically applied by laypersons without any—or at least with a significantly reduced—risk of causing injuries to the subject. In particular, it is an object of the present invention to provide a method of capturing images that allows for reliable identification of objects, especially the eardrum, without the need of introducing an otoscope as far as considerably within a section of the ear canal which is confined by hard bone. The object of the present invention can also be describes as to provide a method that allows for reliable identification of objects, especially the ear drum, substantially irrespective of any experience or knowledge with respect to the correct relative position of a head portion of an otoscope within the ear canal.
That object is achieved according to the present invention by a method exhibiting the features of claim 1. Preferred embodiments of the present invention are provided by the dependent claims.
In particular, that object is achieved by a method of identifying objects in a subject's ear, comprising the following steps: introducing an optical electronic imaging unit and at least one light source into an ear canal of a subject's outer ear, wherein the electronic imaging unit exhibits at least one optical axis directed in a distal direction, especially at the eardrum of the subject's ear; using the electronic imaging unit to capture at least one image from at least one eccentric observation point positioned on the at least one optical axis and positioned eccentrically within the ear canal; and determining brightness and/or color information to identify objects shown in the at least one image by electronic means, in order to automatically identify the objects, especially the eardrum. Such a method even allows for identification of objects which are arranged deep within the ear canal, e.g. the eardrum, even in case the electronic imaging unit is only introduced as far as a curvature or a transition area between soft tissue and hard bone confining the ear canal.
An electronic imaging unit according to the invention is preferably based on optical imaging and preferably comprises at least one optical camera defining an optical axis and/or comprises at least two optical axes defined by beam splitter optics.
As described above, in many cases, the optics of an otoscope adapted to carry out the otoscopic method according to art—comprising a lamp and a lens—are positioned anywhere between a proximal end and the distal end of the head portion, especially at the wider end of the funnel, i.e. not at the distal end of the head portion. As a consequence, the longitudinal axis of the head portion forms the optical axis of the otoscope. The optical axis has to directly point to the eardrum for enabling visual access through the ear canal to the eardrum. In order to enable such visual access state of the art methods require the practitioner to significantly deform the subject's ear, namely straightening the ear canal, and further require introducing a relatively narrow tip of the funnel deeply into the subject's ear canal, especially deeply into the bony part of the ear canal.
Introducing an electronic imaging unit which provides at least one eccentric observation point and/or at least one light source (preferably both) into an ear canal of a subject's outer ear and capturing imaged from the eccentric position—according to the method of the present invention—overcomes these disadvantages of such prior art methods using known otoscopes. In particular, an optical axis of an otoscope used for carrying out the method of the present invention does not have to correspond to the longitudinal axis of the head portion. Instead, an optical axis of the electronic imaging unit may be arranged radially offset.
In particular, in many cases, the ear canal of the outer ear is not straight-lined, but exhibits at least one curvature, especially at a transition area or transition point between soft connective tissue and hard bone confining the ear canal. The “corner” is provided by this curvature. Consequently, when carrying out the method of the present invention, the requirement to deform the subject's ear is eliminated or greatly reduced. Furthermore, the inventive method avoids the risk of injury to the ear canal, in particular the bony part of the ear canal, or to the eardrum by allowing the use of otoscopes with a tip of the head portion that exhibit significantly larger dimensions as compared to an otoscope according to the art. Thus, the risk of introducing the head portion of the otoscope too deeply into the subject's ear canal is considerably reduced. Both improvements pave the way to allow laypersons to carry out the method according to the invention.
An eccentric position or observation point allows for “looking around the corner”. In particular, the eardrum can be observed in its entirety, even in case the distal tip of an otoscope is introduced only as far as a transition area between soft connective tissue and hard bone confining the ear canal. The larger the radial offset, the better the view onto the eardrum, even in case a distal end of an otoscope is positioned only in a transition area between soft connective tissue and hard bone confining the ear canal. Preferably, capturing the at least one image is carried out from an eccentric observation point which is positioned closer than 1.5 mm, more preferable closer than 1.0 mm, further preferred closer than 0.8 mm or even closer than 0.7 mm or 0.6 mm to an inner lateral surface of the ear canal, especially with respect to a diameter of the ear canal in the range between 4.8 mm and 5.2 mm. Such a method may be carried out with an otoscope exhibiting a head portion which fits into the ear canal, the head portion having radial dimensions (e.g. 5 mm) which at least approximately correspond to the diameter of the ear canal at a transition area between soft connective tissue and hard bone confining the ear canal.
In particular, a method according to the present invention allows for identifying the ear drum substantially irrespective of the relative position of a head portion of the otoscope within the ear canal, especially irrespective of any specific insertion depth into the bony part of the ear canal, i.e. the section confined by hard bone, or irrespective of any specific orientation of the head portion or a handle portion of the otoscope.
Preferably, an “optical axis of the electronic imaging unit” is an axis which extends from a most distal point of the electronic imaging unit in a distal direction, especially towards the eardrum, wherein its orientation is not modified any more by any optical components. The “optical axis of the electronic imaging unit” of an electronic imaging unit preferably is the optical axis with the largest radial offset.
As a further advantage of the present inventive method it enables the use of imaging devices which provide a larger field of vision. An optical component defining the field (or angle) of vision of the electronic imaging unit of such devices can be positioned at the distal end of the head portion, especially at the distal tip. Thereby, a much larger the field (or angle) of vision is obtainable than by methods which are based on the relatively acute empty funnel of an otoscope according to the prior art.
Once at least one image has been captured by the at least on electronic imaging unit, object recognition and unambiguous object identification (e.g. distinguishing objects, such as earwax, hair, and the eardrum) can be performed by determining brightness and/or color information of the pixels of the at least one captured image. Each pixel of the image obtained by the electronic imaging unit is characterized by a numerical value corresponding to the brightness of that pixel and—if the electronic imaging device comprises a color imaging device—also by a numerical value corresponding to the color of that pixel. Different objects can be identified e.g. by their typical color.
In a method according to the present invention, preferably, during capture of the at least one image, the ear canal is illuminated from an eccentric illumination point positioned eccentrically within the ear canal. Such a method allows illuminating the ear canal and even the eardrum, even if the otoscope is introduced only as deep as a transition area between two types of tissue or as a curvature. Such a method allows for providing appropriate illumination of all objects which may be captured from the at least one eccentric observation point.
In a method according to the present invention, the at least one image may be captured along at least one optical axis which is tilted, especially with respect to a longitudinal axis of the ear canal and/or with respect to a longitudinal axis of a head portion of an otoscope used for carrying out the method. A tilted optical axis allows for “looking around the corner” more effectively. In conjunction with an eccentric observation point, “looking around the corner” can be carried out even more effectively.
In other words: In addition to a radially offset arrangement, at lest one optical axis of the electronic imaging unit may be arranged at an angle with respect to the longitudinal axis (tilted against the longitudinal axis), allowing the device to “look around the corner” more effectively, or allowing the device to “look around the corner” even from a central observation point.
In a method according to the present invention, preferably, the method further comprises detecting infrared radiation by means of an infrared sensor unit. Providing a method comprising temperature detection in conjunction with an optical identification of objects allows for more reliable identification of the objects, e.g. of the eardrum. Providing an otoscope additionally with an infrared sensor unit, especially arranged centrically at the distal tip, allows for minimizing any risk of misdiagnosis. The infrared sensor unit can be connected to a logic unit, the logic unit being configured for processing data from both the infrared sensor unit and the electronic imaging unit, especially simultaneously. Data acquired by the infrared sensor unit can be verified based on data acquired by the electronic imaging unit, and vice versa. Brightness data or color information data can be correlated with temperature data. The infrared sensor unit can be provided at same positions like positions discussed in context with the electronic imaging unit or the light sources. Nonetheless, preferably, the infrared sensor unit is arranged for acquiring temperature data from a central point or any point which is arranged radially offset within the semicircle or the quadrant of the cross section of a distal tip of an otoscope in which the radially offset optical axis is arranged. Likewise, the infrared sensor unit can be displaced in the same manner as discussed in context with the electronic imaging unit or the light sources.
For improved object identification, a method according to the present invention preferably further comprises the following steps: using the electronic imaging unit to capture at least two images from different eccentric positions within the ear canal and/or with illumination from different eccentric positions within the ear canal; and comparing the at least two captured images with each other to identify objects shown in the images.
Thus, the above object is solved by a method of identifying objects in a subject's ear may comprise the following steps: introducing an electronic imaging unit and at least one light source into an ear canal of a subject's outer ear; using the electronic imaging unit to capture at least two images from different positions within the ear canal and/or with illumination from different positions within the ear canal; comparing the at least two captured images with each other to reliably identify objects shown in the images.
With these features, the electronic imaging unit is suitable to capture at least two images from different positions within the ear canal, e.g. by relocating one single electronic imaging unit when placed in the subject's ear canal and/or by providing images from two or more electronic imaging units positioned at different sites in the ear canal. Alternatively or additionally, the method may be based on the implementation of at least one illumination unit which is adapted to illuminate objects within the ear canal from different positions (e.g. from two or more positions). Preferably, a combination of both approaches is realized by the inventive method, which allows capturing images from different positions under differing illumination conditions. Such a mode of action allows for reliable identification of distinct objects (e.g. the eardrum, particles of earwax, hair, etc. in the subject's ear), as will be described in more detail below. Thereby, the risk of image misinterpretation and failure in object recognition is significantly reduced.
In a method according to the present invention, preferably, the different positions are defined or adjusted such that the captured images allow for stereoscopic viewing, the different positions being spaced apart from each other in a distance (d) of at least 2 mm or 3 mm, preferably at least 3.5 mm, more preferable at least 3.7 mm, especially between 3.7 mm and 4.4 mm for a distance between the positions for capturing the images, especially between at least two eccentric observation points (EOP), or especially between 3.7 mm and 4.6 mm for a distance between the positions for illumination, especially between at least two eccentric illumination points (EIP). Distances in such a range can ensure that the identified objects can be distinguished by stereoscopic viewing. Preferably, the distance is defined with respect to eccentric observation points. A large distance between different observation points facilitates stereoscopic viewing. Stereoscopic information determined by 3D mapping from parallax images can be determined.
In a method according to the present invention, preferably, the at least two images are captured from at least two different eccentric observation points (EOP), which are preferably arranged at the same radial offset within the ear canal, especially on the same pitch circle concentrically within the ear canal. A large radial offset can ensure that the objects can be observed from directions which vary considerably. Arranging the eccentric observation points (EOP) or optical axes on the same pitch circle allows for automatically displacing a plurality of eccentric observation points (EOP) by rotation, which facilitates differentiation of objects.
In a method according to the present invention, preferably, the at least two images are captured from at least two optical axes of the electronic imaging unit, in particular by a single image sensor of the electronic imaging unit or by at least two cameras of the electronic imaging unit. Alternatively, the at least two images are captured from a single optical axis of the electronic imaging unit. Capturing from different optical axes provides the advantage of e.g. fast acquisition of image data. Capturing from one single optical axes provides the advantage of e.g. acquiring image data continuously, e.g. during displacement of a camera of the electronic imaging unit. In other words: both alternatives provide the advantage of “looking around the corner” more effectively.
In a method according to the present invention, preferably, the at least two images are captured within a specific time frame, especially from at least two eccentric observation points. Time related capture of image data facilitates determining if a respective object is immobile or moves, e.g. an eardrum which is pressurized. For example, 10 or 20 images may be captures per second. At the maximum, e.g., 60 images are captures per second, especially during displacement of the respective optical axis or camera. The number of images captured per second can be adjusted in dependence on a speed of displacement, especially rotation, of the at least one optical axis or the at least one light source. In particular, the number of images captured per second increases with increasing speed of displacement.
In a method according to the present invention, preferably, during capture of the at least two images, illumination is sequentially switched on and off, the at least one light source preferably being provided by an LED, wherein illumination preferably is synchronized with a shutter of the electronic imaging unit. Synchronization with a shutter, i.e. a device that allows light to be collected for a determined period of time, exposing a light-sensitive electronic sensor, allows for exposure of individual frames at different illumination conditions. Such a method facilitates differentiation of objects. Also, such a method may allow for saving electrical power, and for increasing battery life, since illumination may be powered exclusively during exposure time of the imaging sensor.
If at least two images are captured from different positions within the ear canal, different objects, such as the eardrum and other objects are discriminated by comparing their positions as provided in the at least two images. That is, the inventive method makes it possible—in contrast to prior art methods—to determine the distance of various objects in the ear canal with respect to the electronic imaging unit according to the fundamental principle of stereoscopic viewing, also known as “parallax”. Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines. For example, a person closing only his left eye sees objects being relatively close at a position other than by closing only his right eye. However, the person will see relatively remote objects substantially at the same position. The human brain is thus able to determine the distance from the observer to the objects as a result of the parallax phenomenon. The same approach may be realized according to the present inventive method by the use of electronic means, such as a logic unit, when capturing images from different positions within the ear canal. Since the electronic imaging unit will not and cannot be introduced too deeply into the subject's ear canal according to the inventive method, the eardrum, as the membrane (object) terminating the ear canal, is relatively remote with respect to the electronic imaging unit, whereas other objects in the ear canal positioned more proximal to the electronic imaging unit are recognized as being less remote from the imaging unit as reference point. Thus, e.g. the eardrum can be readily distinguished from other objects located more proximal in the ear canal by the inventive method. Furthermore, a pathologic condition of the eardrum due to middle ear disease, e.g. retraction or bulging of the eardrum, can be distinguished. This also allows for better distinguishing between the eardrum and other objects within the ear canal. Alternatively or additionally, different objects, such as earwax, hair, and the eardrum, within the subject's ear canal may be discriminated by comparing their appearance as depicted by at least two images captured under illumination from different positions (for each single image) within the ear canal. If an object positioned relatively closely to the electronic imaging unit, such as earwax, is illuminated from different positions within the ear canal (by e.g. two or more distinct light sources or by e.g. one single light source which can be repositioned when carrying out the inventive method), the appearance of such an object will significantly differ in the at least two images captured according to the inventive method. Usually, the position of the sources of illumination is chosen such that, when carrying out the inventive method, they are still positioned closely to the electronic imaging unit. In contrast thereto, an object positioned relatively remote from the electronic imaging unit, such as the eardrum, will typically not change its appearance in the at least two images captured according to the inventive method by such illumination from different positions.
In a method according to the present invention, preferably, the at least two images are captured with illumination from at least two different eccentric illumination points (EIP), which are preferably arranged at the same radial offset within the ear canal, especially on the same pitch circle concentrically within the ear canal. Illuminating from eccentric illumination points allows for “looking around the corner” more effectively or with a better reliability. Eccentric illumination points enable illumination of the eardrum, especially the entire eardrum, even if a distal tip of an otoscope is introduced only as far as a transition area between soft connective tissue and hard bone confining the ear canal.
In a method according to the present invention, preferably, the at least two images are captured with illumination from at least two illumination axes, in particular by at least two light sources arranged eccentrically within the ear canal, especially at the same radial offset within the ear canal. Alternatively, the at least two images are captured with illumination from a single illumination axis, wherein a light source is displaced within the ear canal. Illuminating from different illumination axes provides the advantage of e.g. fast change or modification of the directions of illumination or light emission. Thereby, separate light sources may illuminate the ear canal without any displacement movement. Illuminating from one single illumination axes provides the advantage of e.g. modifying illumination continuously during displacement of at least one light source, e.g. in order to capture any images at specific instants at which illumination is favorable. In other words: both alternatives provide the advantage of providing favorable illumination conditions.
Furthermore, illumination at different angles may drastically change the reflective pattern and appearance of objects which are arranged close to the electronic imaging unit, while the reflective pattern and appearance of more distant objects only varies slightly. Thus, based on illumination at different angles, i.e. from different eccentric illumination points, the change in appearance can be evaluated in order to estimate the object's distance with respect to the imaging unit.
A method according to the present invention preferably further comprises a step of generating a calculated image based on the at least two captured images. One mode of carrying out the inventive method may be directed to exclusive object recognition of the eardrum. Thereby, the calculated image preferably does not display other more proximal (located more closely to the electronic imaging unit) objects, such as earwax and hair.
Under such circumstances, any object in the ear canal, e.g. a hair, which—at least partially—obstructs the view of the electronic imaging unit at a certain position within the ear canal onto the eardrum, may not prevent the user from obtaining the desired image information. The inventive method still allows to provide either a free view onto the eardrum by the electronic imaging unit, as the method allows to relocate the imaging unit to another position in the ear canal or may thereby at least provide a free view onto the part of the eardrum that was previously partially obstructed by the hair. For such an embodiment of the invention, the objects located relatively closely to the electronic imaging unit, such as earwax and hair, will be preferably identified as well, whereby the inventive method may provide an additional step, e.g. by electronic means, such as a logic unit, of generating a calculated image. Such a calculated image would not display any objects located relatively closely to the electronic imaging unit, such as earwax and hair, if the inventive method—as described for that embodiment—were intended to capture the best image possible of the eardrum. Consequently, an image will be calculated by the inventive method exclusively depicting the eardrum (and its structure), whereas other objects, such as hair and earwax, have been “eliminated” upon their recognition.
The term “relatively closely” in this context preferably refers to a distance of preferably not more than 6 mm, more preferably of no more than 4 mm from the reference point, e.g. the electronic image unit.
The image calculated according to the inventive method may be provided to a user by a display device, or may be stored to a storage card, or may be transferred to an external device via cable or wirelessly. If the calculated image is stored, the user, be it a layperson or a physician, may later analyze the image for whatever purpose.
If the electronic imaging unit comprises at least one color video camera, a method according to the present invention preferably further comprises a step of determining the spectral composition of reflections, especially the degree of reddishness, of any physiological objects in the ear canal (skin of the ear canal or of the eardrum), once the desired object (e.g. the eardrum) has been identified. Determining the spectral composition of reflections of e.g. the eardrum, or an area around the eardrum including the eardrum, may help the layperson to decide as to whether a physician should be visited or not, as it may potentially indicate inflammation of the eardrum. Inflammation of the eardrum may suggest e.g. a (bacterial/viral) infection. Any such more advanced or final disease diagnosis has to be carried out by the physician on the basis of other symptoms exhibited by the subject, which are observed by the physician, or by the physician's further examination. Disease diagnosis can therefore not be derived from the output provided by the method according to the invention, e.g. image information alone. Determining the degree of reddishness may help the layperson to decide not to visit a physician. Reddishness may also be observed elsewhere in the ear canal, as e.g. inflammation may also affect the inner part of the ear canal of the subject's outer ear. Thus, a method according to the present invention may additionally or alternatively determine the spectral composition of reflections of the inner part of the ear canal of the subject's outer ear, upon object recognition of the inner part of the ear canal by the inventive method.
The inventive method is based on an electronic imaging unit which preferably comprises a wide angle video camera, preferably a miniature camera, in particular a wafer-level camera. The term “wide angle” in this context refers to field of view angles of at least 80°, preferably of at least 110°, e.g. 120°. A method based on such wide angle cameras allows for detection of the subject's eardrum, even if the optical axis (corresponding to a “viewing direction”) of the camera is not directly centered to the eardrum when applying the inventive method. The same holds if the eardrum is located—by applying the inventive method—relatively remote from the camera, compared to the distance between the eardrum and the tip end of an otoscope of the art during application. The electronic imaging unit used by a method of the invention may comprise a miniature camera, in particular a wafer-level camera of a substantially flat configuration, having dimensions of less than 3 mm×3 mm, preferably less than 2 mm×2 mm, even more preferable of about 1 mm×1 mm or even less than 1 mm×1 mm. Such a wafer-level camera can be produced nowadays extremely small in size with only about 3 microns per pixel. Therefore, wafer-level imaging technology allows for obtaining images of “sufficient” resolution of the eardrum, e.g. images of 250 pixels×250 pixels, with a footprint of the camera including lens of only about 1 mm×1 mm or even smaller.
The term “miniature camera” refers to cameras having minimum dimensions with respect to the required method of capturing images, preferably lateral or radial dimensions in the range of 0.5 mm to 2.5 mm, more preferably in the range of 0.5 mm to 1.5 mm, or 1 mm. A “miniature camera” may exhibit a diameter in the range of e.g. 0.5 mm to 1.5 mm. The dimensions of the camera in an axial direction (parallel to the longitudinal axis) is circumstantial, i.e. only of minor importance. Radial dimensions of less than 2 mm×2 mm, even more preferable of about 1 mm×1 mm provide the advantage that an optical axis of the electronic imaging unit or camera can be arranged very close to an inner or outer lateral surface of the head portion, thereby enabling the otoscope to “look around the corner” with a relatively big angle, e.g. an angle in the range of 10° to 60°, preferably in the range of 15° to 40°, more preferable in the range of 20° to 30°.
A camera based on wafer technology provides a good compromise between light sensitivity and space requirements. The light sensitivity depends on the dimensions of an aperture or lens of the camera. The bigger the aperture, the higher the light sensitivity.
A wide angle camera may enable the otoscope to “look around the corner”, in particular in conjunction with a radial offset and/or an optical axis which is tilted against the longitudinal axis of the head portion. A radial offset in conjunction with the ability of a “wide angle” may provide the advantage of “looking around the corner” without the need of an optical axis which is tilted. Nonetheless, the ability of “looking around the corner” can be ensured also by a camera being positioned radially offset and having an optical axis which is tilted. Most effectively, the ability of “looking around the corner” can be ensured by a wide angle camera which is positioned radially offset and which also has an optical axis which is tilted.
Preferably, the electronic imaging unit comprises at least three or four cameras, in particular miniature cameras, e.g. wafer-level cameras, which have dimensions such that all cameras can be arranged radially offset (with a maximum radial offset) from the longitudinal axis of the head portion.
In particular, especially with miniature cameras each having dimensions of about or even less than 1 mm×1 mm, a number of three cameras could be sufficient, as such small cameras can be positioned with a relatively high radial offset. The smaller the camera, the larger the realizable radial offset of an optical axis of the camera. A number of only three cameras also provides the advantage of reduced costs. In case the cameras have dimensions of e.g. about 1.2 mm×1.2 mm or 1.5 mm×1.5 mm, a number of four cameras is preferred. The higher the number of the cameras or optical axes, the higher the likelihood that at least one optical axis is positioned at a favorable eccentric position within the ear canal in order to entirely observe the eardrum. According to one embodiment, the electronic imaging unit comprises four cameras arranged at the same radial offset and having the same distance to each other in a circumferential direction.
A number of three, four, five or six miniature cameras or optical axes can eliminate any need for displacement or rotation of the head portion for positioning a camera in a preferred eccentric observation point. For example, with such an arrangement, it can be ensured that the head portion of the otoscope or the handle portion of the otoscope does not have to be rotated at all. In other words: The layperson only has to introduce the otoscope in an axial direction. It is not required to rotate any part of the otoscope. This may reduce the probability of any irritations of the tissue. Also, any prerequisite for skill or training of the layperson may be dispensable. Preferably, the electronic imaging unit exhibits a plurality of optical axes which are arranged rotationally symmetrically with respect to the longitudinal axis of the head portion. According to one embodiment, each optical axis may be provided by one camera.
Nonetheless, irrespective of the number of optical axes, additionally, a motion mechanism can be provided. Providing several cameras, e.g. two cameras, in conjunction with a motion mechanism provides the advantage that, if at all, the head portion or the otoscope only has to be rotated by a maximum angle of about 20° to 50°, in order to displace at least one of the cameras in a preferred position for “looking around the corner”. A rotating movement of maximum 40° or 50° can position at least one of the cameras in a position in which the eardrum is best visible.
The present invention is based on the finding that an angle of 40° or 50° can be handled or operated without any problems, especially in an ergonomic way by laypersons, even in context with an application by the layperson. Thus, providing at least three optical axes may eliminate the need of any motion mechanism. It has been found that more than three or four cameras or optical axes are not necessarily required.
In a method according to the present invention, preferably, determining color information includes evaluation of the spectrum of reflected light, especially light reflected from the eardrum, especially in dependence on a specific intensity of illumination provided by the least one light source. Evaluation of the spectral response can lead to more certain information with respect to the type of tissue observed and/or a possible pathologic condition, e.g. an increased degree of reddishness in inflammation. Evaluation in dependence on the intensity can provide more reliable results, especially with respect to any characteristics of an inner lateral surface of the ear canal, facilitating to distinguish between the eardrum and an inner surface of the ear canal.
In a method according to the present invention, preferably, an intensity of illumination provided by the at least one light source is varied, especially during determination of the spectral composition of reflections, especially such that the degree of reddishness is determined based on at least two different intensities of illumination. Varying the intensity can provide more reliable results, especially with respect to any characteristics of the eardrum. In particular, the spectral composition of reflections can be determined with high accuracy. Preferably, the intensity is varied during the step of capturing a plurality of images, especially continuously varied. This allows for evaluating any change in the degree of reddishness more reliably.
In a method according to the present invention, preferably, a plurality of images is captured, each image being captured at a different intensity of illumination. Acquiring a plurality of images at different illumination levels allows for enhancing the dynamic range of the images. For each pixel, the information contained in the images can be evaluated in more detail. In particular, the method can be carried out with an otoscope which exhibits a logic unit allowing for processing or calculating a calculated image based on the plurality of images acquired at different illumination levels.
In a method according to the present invention, preferably, an intensity of illumination provided by the at least one light source is adjusted, preferably in dependence on reflected radiation as received by the imaging unit, especially such that the subject's tympanic cavity arranged behind the eardrum can be illuminated through the eardrum and reflected light from the tympanic cavity can be r observed. Adjusting the intensity such that the background of the eardrum can be observed enables identification of the eardrum with higher reliability. Thereby, optimally illuminating the eardrum or its background while respecting the dynamic range of the electronic imaging unit facilitates reliable identification of the objects. Furthermore, pathological conditions in the middle ear, i.e. tympanic cavity, can be determined. The present invention is also based on the finding that identification of the tympanic cavity covered by a semitransparent membrane can facilitate identification of the eardrum, as the eardrum is the sole tissue within the outer ear canal which is arranged in front of a cavity. A feedback illumination control can be provided in conjunction with illuminating the eardrum, especially by a logic unit which is coupled with one or several imaging units and light sources.
The present invention is also based on the finding that information relating to characteristics of the patient's tympanic cavity can be evaluated or processed (e.g. by a logic unit) in order to provide the layperson with an advice as to whether a physician should be visited or not. In particular, the present invention is also based on the finding that any serous or mucous fluid within the tympanic cavity can be an indicator of the eardrum itself, and can be an indicator of a pathologic condition in the middle ear. Within the ear canal, only behind the eardrum, such body fluid can be identified. Thus, evidence of any body fluid can provide evidence of the eardrum itself, as well as evidence of a pathologic condition, e.g. OME.
In a method according to the present invention, preferably, an intensity of illumination provided by the at least one light source is adjusted such that light emitted by the at least one light source is arranged for at least partially transilluminating the eardrum in such a way that it can be reflected at least partially by any object or body fluid within the subject's tympanic cavity arranged behind the eardrum. The present invention is based on the finding that translucent characteristics of the eardrum can be evaluated in order to distinguish between different objects within the ear canal, especially in order to identify the eardrum more reliably. Thereby, illumination can be adjusted such that tissue or hard bone confining the ear canal is overexposed, providing reflections (reflected radiation or light), especially reflections within a known spectrum, which can be ignored, i.e. automatically subtracted out. Such a method enables identification of the eardrum more reliably.
In particular, the degree of reddishness or reflectivity of light in the red spectral range can be determined at different illumination intensities. It can therefore be distinguished more reliably between light reflected by the eardrum itself, or by objects or fluids behind the eardrum, or by the mucosal covering the tympanic cavity wall. The reflectivity of light may be evaluated with respect to reflectivity within e.g. the green or blue spectral range. Typical spectral wavelength maxima are 450 nm (blue light), 550 nm (green light), and 600 nm (red light) for a respective (color) channel. The electronic imaging unit, e.g. comprising a color video camera, or any color sensitive sensor, may record images with respect to the red, green or blue spectral range, respectively. A logic unit may calculate, compare and normalize brightness values for each read, green and blue image, especially with respect to each separate pixel of the respective image. Such an evaluation may also facilitate medical characterization of the eardrum. In particular, the healthy eardrum is a thin, semitransparent membrane containing only few relatively small blood vessels. In contrast, an inflamed eardrum may exhibit thickening and/or increased vascularization. Also, any skin or tissue confining the ear canal as well as any mucosa in the middle ear may be heavily vascularized. In other words: The reflectivity in the different spectral ranges varies considerably between the different structures or objects as well as between healthy and inflamed tissue. Thus, referring to the spectral range enables more reliable differentiation between light reflected by the eardrum itself, or by objects or any fluid behind the eardrum, or by the tympanic cavity wall covered by mucosa.
Thereby, the risk of confounding any red (inflamed) section of the ear canal and the eardrum can be minimized. Also, the eardrum can be identified indirectly by identifying the tympanic cavity. In particular, any opaque fluid, especially amber fluid containing leukocytes and proteins, within the tympanic cavity may influence the spectrum of reflected light, depending on the intensity of illumination. At a relatively high intensity of illumination, the spectrum of reflected light will be typical for scattering in serous or mucous fluid containing particles like leukocytes, as light transmits the eardrum and is at least partially reflected by the opaque fluid. At a relatively low intensity of illumination, the spectrum of reflected light will be dominated by the eardrum itself, as a considerable fraction of the light does not transmit the eardrum, but is directly reflected by the eardrum. Thus, information relating to the tympanic cavity, especially more detailed color information, can facilitate identification of the eardrum as well as of pathologic conditions in the middle ear.
In particular, the present invention is also based on the finding that transilluminating the eardrum can provide supplemental information with respect to the characteristics of the eardrum (e.g. the shape, especially a convexity of the eardrum), and/or with respect to the presence of any fluid within the tympanic cavity. Spectral patterns of reflected light which are typical for eardrum reflection and tympanic cavity reflection can be use to determine the area of interest as well as a physiologic or pathologic condition of the eardrum and the tympanic cavity, especially in conjunction with feedback controlled illumination.
The present invention is also based on the finding that any fluid within the tympanic cavity evokes a higher degree of reflection than the physiologically present air. The fluid increases reflectance. In contrast, in case the tympanic cavity is filled with air, any light transilluminating the eardrum is only reflected with inferior intensity, as most of the light is absorbed within the tympanic cavity. In other words: transilluminating the eardrum and evaluating reflected light in dependence on the intensity of illumination can facilitate determining specific characteristics of the eardrum, e.g. an absolute degree of reflectivity in dependence on different wavelengths and intensities, providing more information or more certain information with respect to the type of tissue and its condition. Evaluating reflected light can comprise spectral analysis of translucent reflection, especially at different illumination intensities.
The present invention is also based on the finding that the degree of reflection in the red spectrum from the area of the eardrum may depend on the illumination level, i.e. the intensity of illumination. In particular, the red channel reflection can increase with increasing intensity of illumination. The higher the intensity of illumination, the higher the red channel reflection intensity. Also, it has been found that at relatively high intensities of illumination, not only the eardrum, but also any other tissue will reflect more light in the red spectrum. Therefore, on the one hand, providing a control or logic unit which is arranged for adjusting the intensity of illumination can facilitate identification of the eardrum. On the other hand, it can facilitate determining specific characteristics of the eardrum, e.g. an absolute degree of red channel reflection, such that the red channel reflection provides more information or more certain information with respect to the type of tissue and state of the tissue.
In particular, the present invention is also based on the finding that the degree of red channel reflection does not increase in the same manner with increasing intensity of illumination, depending on the presence of body fluid behind the eardrum. It has been found that in case there is body fluid within the tympanic cavity, with increasing intensity of illumination, the degree of red channel reflection does not increase as strongly as if the tympanic cavity was empty. Thus, based on the (absolute) degree of red channel reflection, the presence of fluid behind the eardrum can be evaluated. This may facilitate determination of pathologic conditions, e.g. OME.
In a method according to the present invention, preferably, identifying objects comprises pattern recognition of geometrical patterns, especially circular or ellipsoid shapes, or geometrical patterns characterizing the malleus bone, or further anatomical characteristics of the outer ear or the middle ear. Pattern recognition allows for more reliable identification of the eardrum. Pattern recognition can comprise recognition based on features and shapes such as the shape of e.g. the malleus, the malleus handle, the eardrum or specific portions of the eardrum such as the pasr flaccida or the fibrocartilagenous ring. In particular, pattern recognition may comprise edge detection and/or spectral analysis, especially shape detection of a circular or ellipsoid shape with an angular interruption at the malleus bone or pars flaccida.
In a method according to the present invention, preferably, pattern recognition is based on determination of an angle or range of angles of the objects, especially an angle with respect to an inner lateral surface of the ear canal or a longitudinal axis of the ear canal. Evaluation of the angle allows for more reliable identification of objects, especially the eardrum. Typically, the ear drum is arranged at an angle of about 30° to 60°, especially 40° to 50° with respect to an inner lateral surface of the ear canal or to a longitudinal axis of a section of the ear canal of the outer ear adjacent to the eardrum. It has been found that this anatomical characteristic can be used in order to facilitate identification of the eardrum, especially based on the assumption that any other objects within the ear canal are not arranged at any (single) specific angle.
Preferably, this method can be carried out with an otoscope comprising a logic unit which is arranged to determine the angle of any object which is identified, especially the angle with respect to a longitudinal axis of a head portion of the otoscope, and/or the angle with respect to a longitudinal axis of the ear canal.
In a method according to the present invention, preferably, identifying objects comprises determining the distance of the objects within the ear canal, especially with respect to an observation point of the electronic imaging unit. The present invention is also based on the finding that differentiation of different objects, especially identification of the eardrum can be facilitated by determining the most distant object within the ear canal of the outer ear. From an observation point within the ear canal of the outer ear, the eardrum is the most distant object.
In particular, the eardrum can be identified more reliably by evaluating if the distance of an object within the ear canal varied for a specific amount. The diameter of the eardrum typically is in the range between 8 mm and 11 mm. As the eardrum typically is arranged at an angle of about 30° to 60°, especially 40° to 50° with respect to an inner lateral surface or a longitudinal axis of the ear canal of the outer ear, the distance of the eardrum to an observation point considerably varies, especially in the range of about ±3 mm or 3.5 mm (maximum variation of about 5.5 mm to 7.5 mm).
Preferably, this method can be carried out with an otoscope comprising a logic unit which is arranged to determine the distance of any object which is identified.
In a method according to the present invention, preferably, the method further comprises calibrating a spectral sensitivity of the electronic imaging unit and/or calibrating color and/or brightness of the at least one light source. Calibration allows for more reliable identification of objects. It has been found that in case the light intensity is very high allowing for passing light through a healthy eardrum, which is semitransparent, a considerable amount of light within the red spectrum can be reflected by the tympanic cavity (especially due to illumination of red mucosa confining the middle ear). Thus, calibrating brightness or the intensity of emitted light enables more accurate evaluation of the (absolute) degree of red channel reflection and its source. In other words, spectral calibration of the imaging sensor in combination with spectral calibration of the illumination means allows for the evaluation of the tissue types and conditions.
In particular, with a method comprising calibration, any (actual) varying voltage of any batteries of an otoscope for carrying out the method does not imply or implicate any source of error. Using traditional otoscopes, it is likely that at low voltage, the spectrum of the illumination is shifted towards the red spectrum, i.e. less energy intensive wavelength, especially when using halogen light bulbs. Calibrating the spectral range and/or the intensity of illumination enables absolute spectral analysis. In other words: the electronic imaging unit can be provided with a calibrated color balance.
Calibration can be carried out e.g. based on feedback illumination control with respect to different objects or different kinds of tissue, once the respective object or tissue has been identified. Thereby, spectral norm curves with respect to different light intensities provide further data based on which calibration can be carried out.
A method according to the present invention preferably further comprises a step of informing the user correspondingly, if identification of the eardrum has failed. For example, it may be impossible for the electronic imaging unit to detect the eardrum and/or the inner part of the ear canal—irrespective of the position of the electronic imaging unit within the ear canal—because the ear canal is blocked by massive earwax or other particles. Alternatively, the eardrum may not be identified because the user did not carry out the inventive method due to inappropriate handling of the corresponding device (otoscope). In such a case, the user may try to repeat to carry out the method according to the present invention by re-adapting the position of the otoscope device in a correct manner, or by cleaning the ear canal.
In a method according to the present invention, preferably, the user is informed by an acoustic signal, especially an acoustic signal emitted outside of the ear canal, and/or by a visual signal. Emitting the acoustic signal out of the patient's ear which is inspected prevents that the patient is irritated by any sound. This enables calmly carrying on with diagnosis, especially self-diagnosis. Alternatively or in addition, a visual signal can provide any information, also additional information. A visual signal can be recognized by the user, even in context with self-diagnosis, e.g. in front of a mirror.
In a method according to the present invention, the at least one optical axis of the electronic imaging unit and/or the at least one light source is preferably displaced within the ear canal of the subject's outer ear along a predetermined path and/or by a predetermined distance between the moment of capturing a first image and the moment of capturing a second image. In order to allow for a relatively simple structural implementation of a corresponding motion mechanism for displacing the electronic imaging unit and/or the at least one light source within the ear canal, the predetermined path has preferably a circular form. Moreover, in order to clearly see a difference between the positions of an object shown in two images captured from different positions within the ear canal (according to the parallax phenomenon described above), the predetermined distance preferably amounts to at least about 1 mm.
In a method according to the present invention, preferably, the first and second images are captured during or before and after displacement of the at least one optical axis and/or the at least one light source. This enables fast acquisition of a plurality of images from favorable points of observation, which do not have to be predefined. Evaluation can be made based on the most favorable images, e.g. the images captures during most favorable illumination conditions.
Preferably, the electronic imaging unit or any component thereof, especially a camera, and the at least one light source are introduced into the ear canal of the subject's outer ear no further than to a distance from the eardrum of at least a few millimeters, preferably of at least 3 mm, more preferable of at least 10 mm, further preferred of at least 15 mm. This securely avoids injuries of the eardrum. As mentioned above, in order to avoid deeper introduction, the tip of the head portion of an otoscope adapted to carry out a method according to the present invention can exhibit greater dimensions compared to the otoscopes known in the art.
In a method according to the present invention, preferably, the electronic imaging unit and the at least one light source are introduced only as deep as not to touch a part of the ear canal which is confined by hard bone, or only as deep as a transition area between soft connective tissue and hard bone confining the ear canal. Such a short insertion depth facilitates or enables carrying out the method by laypersons.
In a method according to the present invention, preferably, the at least one image is captured from an eccentric observation point (EOP), especially on an optical axis which is tilted against a longitudinal axis of the ear canal or against a longitudinal axis of a head portion of an otoscope used for carrying out the method, such that the electronic imaging unit or at least one camera of the electronic imaging unit looks around a curvature of the ear canal. An eccentric observation point in conjunction with a tilted optical axis allows for effectively “looking around the corner” such that the eardrum can be observed from a point of observation which is arranged at a transition area between soft connective tissue and hard bone confining the ear canal. An eccentric observation point in conjunction with a tilted optical axis allows for introducing the distal tip not very deep, which ensures secure handling, even by laypersons.
In order to carry out the method of the present invention, preferably an otoscope is used, comprising a handle portion allowing a user to manipulate the otoscope during its application; and a head portion exhibiting a substantially tapering form extending along a longitudinal axis of the head portion, wherein the head portion has a proximal end adjacent to the handle portion and a smaller distal end configured to be introduced into the ear canal of the subject's outer ear. These features are also known from an otoscope of the art as described above. However, the otoscope used for carrying out the present invention preferably further comprises the electronic imaging unit, especially a camera, positioned in the distal end of the head portion, especially at a distal tip of the head portion, the at least one optical axis being positioned radially offset from the longitudinal axis, the radial offset preferably being at least factor 0.25 of the radial dimension of the distal end, more preferable at least factor 0.3, further preferred at least factor 0.35. Such a relatively large radial offset can ensure positioning the optical axis in a favorable eccentric observation point within the ear canal, even in case the distal tip in introduced only as deep as a transition point between soft connective tissue and hard bone.
Alternatively or in addition, the image can be captured from an observation point which is arranged eccentrically within the ear canal, wherein at least one of the at least one optical axis of the electronic imaging unit is be positioned radially offset from the longitudinal axis of the head portion. Such a configuration also allows obtaining a free view onto the eardrum without having to introduce the electronic imaging unit as deeply as it would be necessary if the electronic imaging unit were placed just centrally on the longitudinal axis of the head portion. The offset may be at least 1 mm, preferably at least 1.5 mm, more preferably at least 1.8 mm or 2 mm from the longitudinal axis.
When introducing the tip end of the head portion no deeper into the ear canal than to the border between the outer part and the inner part of the outer ear canal of the subject's outer ear, i.e. to a transition area between the two types of tissue, there is the risk that artifacts, such as earwax, hair and other kind of dirt from the outer part of the outer ear canal obstruct the view of the small electronic imaging unit onto the subject's eardrum. Therefore, it is advantageous to capture several images from different positions within the ear canal, especially from different eccentric optical axes. For doing so, the otoscope adapted for performing a method according to the present invention may comprise more than one optical axis, e.g. a plurality of optical axis provided by several cameras of the electronic imaging unit, and/or by beam splitter optics of the electronic imaging unit, positioned at the distal end of its head portion, respectively, and located at different positions on the head portion.
Providing a relatively small electronic imaging unit at the distal end of the head portion exhibiting at least one optical axis which is radially offset allows to “see” the patient's eardrum without the need to deform the patient's ear canal, or at least without having to deform the ear canal to such an extent as with the above described conventional otoscope. The reason for this is that there is no need for the “viewing direction” of the electronic imaging unit to correspond to the longitudinal axis of the head portion of the otoscope. Rather, the radial offset can ensure that there is a line of sight onto the eardrum even if the ear canal is not straightened, allowing the device to “look around the corner”. In particular, in many cases, the ear canal of the outer ear is not straight-lined, but exhibits at least one curvature, especially at a transition area or transition point between soft connective tissue and hard bone confining the ear canal. The “corner” is provided by this curvature. In particular, virtually almost always, the ear canal has an S-shaped (sigmoid) form with a first curvature and a second curvature, the second curvature being closer to the eardrum than the first curvature. Particularly, the second curvature of the ear canal obstructs any optical line of sight or visual communication of an otoscope which is not introduced as far as at least some millimeters within the bony part of the ear canal. The “corner” can be defined as the second curvature of the ear canal. In particular, in a distal direction, the second curvature leads to the bony part of the ear canal. A transition point or area between soft connective tissue and hard bone is arranged at this second curvature. The second curvature leads into the section of the ear canal which is exclusively confined by hard bone. Preferably, the transition area can be defined as an area of about a few millimeters distal to (behind) and about a few millimeters proximal to (in front of) a curvature, especially 0 mm to 5 mm or 1 mm to 3 mm.
Such an electronic imaging unit can provide an otoscope which can be used by laypersons, without extensive otoscopy training and with a significantly reduced risk of causing injuries, especially with a significantly reduced risk of irritation of the patient's tissue, e.g. the tissue within the hard bone section of the ear canal. Such an electronic imaging unit allows for observing the eardrum substantially irrespective of the relative position of a head portion of the otoscope within the ear canal, especially irrespective of any specific insertion depth into the bony part of the ear canal, i.e. the section confined by hard bone. As the otoscope is arranged for “looking around the corner or curvature”, the layperson does not have to introduce the head portion as far as a section of the ear canal which is confined by hard bone. While in traditional otoscopy, the physician has to introduce the otoscope at least as far as some millimeters within the bony part of the ear canal, i.e. considerably further inwards than the second curvature, an otoscope according to the present invention can be positioned adjacent to the second curvature. In traditional otoscopy, the otoscope is necessarily introduced far into the bony part of the ear canal, especially in order to provide a kind of support or rest or anchoring point at the distal tip of the otoscope. Once the distal tip of the otoscope is supported within the bony part, the physician can apply a leverage on the handle portion of the otoscope, in order to straighten the ear canal and in order to ensure an optical line of sight onto the eardrum. But, this kind of “alignment” of the otoscope or this kind of straightening out the ear canal is painful. In contrast, the otoscope according to the invention does not require such an “alignment” or straightening.
Preferably, the at least one miniature camera and/or any other optical unit or light source are positioned at a distance of less than 3 mm, preferably less than 2 mm, more preferable less than 1 mm, from the distal tip of the head portion, such that these components are introduced as deep as possible with respect to the position of the distal tip within the ear canal. Such an arrangement, especially as close as possible to the distal tip, allows for providing the maximum eccentricity within the ear canal, allowing for effectively “looking around the corner”.
One optical axis of the electronic imaging unit may be positioned substantially centrically with respect to the longitudinal axis of the head portion. If one optical axis of the electronic imaging unit is positioned on the longitudinal axis of the head portion, a substantially flat optical component of the electronic imaging unit is preferable inclined or inclinable with respect of the longitudinal axis of the head portion, so that the one optical axis (or a “viewing direction”) of the electronic imaging unit is angled with respect to the longitudinal axis of the head portion (tilted against the longitudinal axis), allowing the otoscope to “look around the corner” even from a central observation point.
In a method according to the present invention, preferably, at least two images are captured using at least two cameras of the electronic imaging unit each defining an optical axis of the electronic imaging unit and/or using beams splitter optics defining at least two optical axes, wherein the beams splitter optics preferably are used in conjunction with a single image sensor. Both alternative methods provide image data which can be evaluated in more detail than image data acquired from a single eccentric observation point. A plurality of different eccentric observation points facilitates e.g. evaluation of distances or three-dimensional shapes.
In case the electronic imaging unit exhibits beam splitter optics defining at least two optical axes which are arranged radially offset from the longitudinal axis, any objects, especially the eardrum, can be observed from different points of the distal tip of the head portion, without the need of a plurality of cameras. With beam splitter optics, a relatively large radial offset of each optical axis can be realized, especially a radial offset which can be even larger than the radial offset of a camera or a relatively small miniature camera. In particular, optical components of the beam splitter optics, such as lenses, mirrors or prisms, can be provided with relatively small radial dimensions. In particular, the optical components can be provided with a radial dimension or diameter smaller than 1 mm, preferably smaller than 0.9 mm, even smaller than 0.8 mm or 0.7 mm.
Also, beam splitter optics can provide an aperture which exhibits relatively large radial dimensions. A large aperture provides for good optical characteristics, especially good light sensitivity and/or a high dynamic range. Further, beam splitter optics can provide an arrangement for “looking around the corner” which is cost-effective.
Preferably, the beam splitter optics define a plurality of optical axes which are arranged rotationally symmetrically with respect to the longitudinal axis of the head portion. Such a design can ensure that the orientation of the head portion within the ear canal can be chosen freely by the user. The user does not have to orientate the handle portion of the otoscope in a specific direction.
Preferably, the electronic imaging unit exhibits an image sensor which is optically coupled with the beam splitter optics, especially with at least two of the optical axes, and which is positioned centrically on the longitudinal axis. An image sensor which is positioned centrically can provide a symmetric design of the imaging unit, which can be favorable also in view of constructing or manufacturing aspects. An image sensor which is arranged centrically can exhibit large radial dimensions, especially as the image sensor can be arranged more proximal in a section of the head portion which exhibits larger radial dimensions than the distal tip. Preferably, the image sensor is provided in conjunction with a plurality of optical axes, e.g. in conjunction with beam splitter optics. In other words: The electronic imaging unit is configured for providing an arrangement with a single image sensor and multiple optical axes. Reducing the number of image sensors can provide an otoscope with a straightforward design, which is cost-effective.
In a method according to the present invention, preferably, capturing the at least one image is carried out from a position within the ear canal in which the at least one optical axis is arranged at or adjacent to a transition point between soft connective tissue and hard bone confining the ear canal, especially in a maximum distance of 0 mm to 5 mm, preferably 1 mm to 3 mm. A maximum distance of 0 mm to 5 mm, preferably 1 mm to 3 mm with respect to the transition point or area allows for a minimum insertion depth.
In a method according to the present invention, preferably, at least one optical axis of the electronic imaging unit is parallel to the longitudinal axis or is tilted against the longitudinal axis, especially with a tilt angle (β) in the range of 10° to 60°, preferably in the range of 15° to 40°, more preferable in the range of 20° to 30. The optical axis is not necessarily tilted. Rather, an eccentric observation point and/or a field of vision exhibiting a wide angle, especially in conjunction with a miniature camera, allows for looking around a curvature, respectively.
In a method according to the present invention, preferably, at least two images are captured from at least two optical axes, preferably three or four optical axes, which are positioned in a predefined geometrical arrangement with respect to each other, especially with a maximum distance to each other and on the same pitch circle. A plurality of optical axes, especially arranged rotationally symmetrically on the same pitch circle with a maximum radial offset, facilitates capturing a plurality of images within short time. In particular, the ear canal can be observed from multiple favorable observation points at the same time, which may facilitate identification of objects, as it can be precluded that the user modifies the relative position of the head portion within the ear canal. Also, the predefined geometrical arrangement may facilitate evaluation of image data.
In a method according to the present invention, preferably, the at least one optical axis and/or the at least one light source is rotated, especially with respect to the handle portion. Displacement, especially rotation, of at least one optical axis allows for positioning the observation point in a most favorable position, substantially irrespective of the arrangement (orientation or depth) of the head portion within the ear canal. Also, multiple radially displaced cameras can be located at different preselected rotational locations (eccentric observation points).
In a method according to the present invention, preferably, the electronic imaging unit or camera or at least one optical axis and/or the at least one light source is rotated on a pitch circle having a maximum radial offset with respect to a diameter of a distal tip of the head portion. The maximum radial offset allows for favorable positions for observing the entire eardrum, even if the head portion is introduced only within the soft connective tissue (not contacting any bony part of the ear canal), or even if the position is unfavorable, e.g. because the layperson does not orientate or align the head portion correctly with respect to the longitudinal axis of the inner part of the ear canal.
In another preferred embodiment, the otoscope may further comprise a motion mechanism configured to allow displacement, especially along a predefined motion path, of the electronic imaging unit or the at least one optical axis and/or the at least one light source relative to the handle portion. With such a motion mechanism, it is possible to position the at least one optical axis in a favorable eccentric observation point, substantially irrespective of the position of the head portion within the ear canal. Also, it is possible to capture a plurality of images from different positions by one single camera or from one optical axis within the subject's ear canal, thereby avoiding the need for two or more cameras.
In a method according to the present invention, preferably, the electronic imaging unit or the at least one optical axis and/or the at least one light source is rotated by a motor, especially a brushless motor of a motion mechanism. Automatized displacement of a (respective) optical axis provides an otoscope which can be handled by layperson without any problems. The layperson does not have to align or orientate the head portion within the ear canal in any specific way. The layperson only has to introduce the head portion as far as a transition area. Additionally, a guidance system may guide the user in order to ensure an appropriate alignment and appropriate insertion depth.
In a method according to the present invention, preferably, identifying objects comprises determining the distance of the objects within the ear canal during rotation or from at least two different eccentric observation points. According to the invention, based on at least two different images taken from at least two different eccentric observation points, it has been found that the eardrum can be identified relatively easily. Typically, the ear drum is tilted at an angle of about 30° to 80° with respect to a longitudinal axis of the inner part of the ear canal. It has been found that two different eccentric observation points provided on a distal tip of a head portion of an otoscope arranged at least approximately concentrically within the ear canal of the outer ear are likely to be arranged at a different distance with respect to the respective opposing section of the eardrum. The front surface of the distal tip preferably is arranged at least approximately orthogonally with respect to the longitudinal axis of the ear canal of the outer ear. At least, the front surface is arranged at an angle with respect to an inner surface of the ear canal which is smaller than the angle at which the ear drum is arranged with respect to the inner lateral surface or a longitudinal axis of the ear canal. Therefore, almost inevitably or certainly, two different eccentric observation points provided on the distal tip are arranged at a different distance.
The otoscope may comprise a motion mechanism which is preferably configured to allow for at least partial rotation of the electronic imaging unit or the at least one optical axis and/or the at least one light source about an axis of rotation. The axis of rotation may correspond to the longitudinal axis of the head portion, especially along a predefined motion path. By displacing the electronic imaging unit along a predefined motion path, it is possible to automatically calculate the distance of the electronic imaging unit to the detected objects, as described above. In view of the typical size of objects found in the ear canal, such as hair and earwax particles, the motion mechanism preferably allows for displacement of the at least one optical axis of at least 1 mm, more preferable at least 2 mm, further preferred at least 3 mm, within the subject's ear canal. For example, in case a radial offset of 1.8 mm or 2 mm is realized, a rotation of 90° evokes a displacement of about 3 mm. A rotation of at least 90°, more preferably of at least 120°, even more preferably of 180° or even more degrees around the axis of rotation may be realized. In conjunction with an electronic imaging unit exhibiting two optical axes or comprising two cameras, a rotation of maximum 90° may be adequate in order to find the most favorable eccentric observation point. In conjunction with an electronic imaging unit exhibiting three optical axes or comprising three cameras, a rotation of maximum 60° or 70° may be adequate. Preferably, the motion mechanism allows for rotation in both directions, i.e. clockwise and counter-clockwise. The motion mechanism may also allow for rotational displacement about more than one axis. The motion mechanism may comprise at least one motor and one or more gears and/or bearings. The electronic imaging unit may be connected to a flexible cable, e.g. a flexible ribbon cable, to allow for such a movement.
An axis of rotation corresponding to the longitudinal axis of the head portion allows for displacing the at least one optical axis concentrically around the longitudinal axis. Thus, irrespective of the relative position of the optical axis, a maximum radial offset can be ensured.
In a method according to the present invention, preferably, the motion mechanism comprises a motor and is arranged for rotation about an axis of rotation, wherein the axis of rotation preferably corresponds to the longitudinal axis of the head portion. Such an arrangement ensures that the most favorable eccentric observation point can be found, at the lastest after having rotated the at least one optical axis around the longitudinal axis of the head portion for about 330° to 360°. Rotation can be carried out at a speed which is adjusted with respect to a preferred exposure time for capturing the images. Preferably, every 10°, an image or frame may be captured.
In a method according to the present invention, preferably, the electronic imaging unit or the at least one optical axis and/or the at least one light source is rotated such that it is positioned at the side of the ear canal which exhibits a relatively large radius of curvature. It has been found that from an eccentric observation point, the eardrum can be observed particularly well in case the eccentric observation point is positioned in a position next to a section of the ear canal exhibiting a large radius of curvature. In particular, in such a section, any getting out of position or any unintended displacement of the head portion does not affect the visibility of the eardrum as negatively as in a section of the ear canal exhibiting a small radius of curvature. In other words: positioning the eccentric observation point at a section of the ear canal exhibiting a high radius of curvature facilitates use of the otoscope by laypersons.
It has been found that an optimal eccentric position (eccentric observation point or eccentric illumination point) can be defined with respect to the smallest radius of curvature of the bend of the ear canal. In particular, the optimal eccentric position can be defined as a position which is laterally opposite of the smallest radius of curvature, i.e. as a position adjacent to the largest radius of curvature at the transition area between the two types of tissue or at the bend of the ear canal.
In a method according to the present invention, preferably, the at least one light source is rotated so as to maintain a predetermined distance with respect to the electronic imaging unit or the at least one optical axis, when the electronic imaging unit or the at least one optical axis is rotated by the motion mechanism. Such a method is advantageous, because the predetermined distal relationship between the at least one light source and the optical axis allows for improved (automatic) image analysis. If a motion mechanism is provided, the motion mechanism preferably also displaces the at least one light source. If the light source is provided in the form of a light guide, the light guide should be sufficiently flexible to allow for such a displacement of the at least one light source. Preferably, the light guide is fixed distally within the head portion, wherein the light guide is elastic, the elasticity allowing for bending and/or twisting. Alternatively, the light guide may be rigid, wherein the entire lightning apparatus may be displaced in conjunction with the head portion.
In a method according to the present invention, preferably, the at least one light source is rotated by rotating the electronic imaging unit, such that the motion mechanism allows for at least partial rotation of both the at least one light source and the electronic imaging unit by rotating the electronic imaging unit. Rotating the light source by means of the electronic imaging unit allows maintaining a predetermined distance there between with a high reliability.
Preferably, the electronic imaging unit or an optical component thereof, e.g. a camera, or the at least one optical axis and/or the at least one light source is tilted against an axis of rotation or against the longitudinal axis, so as to be continuously directed to a predetermined point on the axis of rotation or the longitudinal axis, the predetermined point having a fixed distance to the electronic imaging unit. In view of the typical length of the inner part of the outer ear canal of the subject's outer ear, the distance may be between 3 mm and 20 mm, preferably between 10 mm and 15 mm. Thus, an optical axis (corresponding to a “viewing direction”) of the electronic imaging unit is optimized for centering on the eardrum.
In a method according to the present invention, preferably, the electronic imaging unit or the at least one optical axis and/or the at least one light source is tilted by a tilting mechanism, preferably at a tilt angle in a range between 10° and 50°, more preferably 20° and 40°, especially subsequent to the step of introducing the electronic imaging unit. A tilting mechanism allows for “looking around the corner” even more effectively. In case the head portion is positioned unfavorably, especially by a layperson, the tilting mechanism can ensure that the eardrum is visible anyhow. The tilting mechanism may be provided in conjunction with a motion mechanism. In particular, the motion mechanism may comprise a tilting mechanism.
In a method according to the present invention, preferably, displacement of the electronic imaging unit or at least one optical axis of the electronic imaging unit relative to the handle portion and/or tilting of the electronic imaging unit or the at least one optical axis against the longitudinal axis is carried out. Two motions, especially two motions which are controlled in dependence on each other, allow for “looking around the corner” more effectively. In particular, axially displacing or rotating an optical axis in conjunction with tilting the optical axis can enable observation of the entire eardrum, even from an observation point with a relatively small radial offset, or positioned unfavorably within the ear canal.
In other words: The otoscope may further comprising at least one mechanism configured to allow displacement of the electronic imaging unit or the at least one optical axis or at least one camera of the electronic imaging unit relative to the handle portion in conjunction with tilting it against the longitudinal axis. Such a combined mechanism, or two motion mechanisms combined with each other, especially two motion mechanisms which are controllable in dependence on each other, allow for “looking around the corner” more effectively. In particular, axially displacing or rotating an optical axis in conjunction with tilting the optical axis can enable observation of the entire eardrum, even from an observation point with a relatively small radial offset, or positioned unfavorably within the ear canal.
The head portion of the otoscope for carrying out the inventive method is preferably shaped in such a way that its distal end comprising the electronic imaging unit or optical component (e.g. camera) can be introduced only as deep into the ear canal as not to touch the eardrum, especially only as deep as a transition area between soft connective tissue and hard bone confining the ear canal. The ear canal of the subject's outer ear is limited by the eardrum. Notably, the ear canal of the subject's outer ear comprises an outer part which refers to a portion of the subject's outer ear (i.e. the subject's external auditory canal) that is surrounded by soft connective tissue and that usually contains hair and earwax. The outer part comprises approximately the outer half of the ear canal of the subject's outer ear. Furthermore, the ear canal of the subject's outer ear also comprises an inner part which refers to a portion of the subject's outer ear (i.e. the subject's external auditory canal) that is surrounded by hard skull bone and that is usually free from any hair and earwax. This portion extends from the proximal end of the outer part of the ear canal of the subject's outer ear to the eardrum. The inner part of the ear canal is very sensitive to pain in case of injury by mechanical friction. Injuring the inner part of the ear canal even bears the risk of cardiovascular complications through vagal overstimulation.
In a method according to the present invention, preferably, the head portion is introduced only as deep as a transition area between soft connective tissue and hard bone confining the ear canal, wherein the head portion is blocked within the ear canal. Preferably, the head portion exhibits a conical shape and the distal end exhibits a minimum diameter in the range of 4 mm to 6 mm, preferably 4.5 mm to 5.3 mm, further preferred 4.7 mm to 5.1 mm, especially 4.9 mm. Mechanically blocking the distal tip within the ear canal allows for secure handling.
Preferably, a tip portion of the distal end can be introduced into the ear canal of the subject's outer ear no further than to a distance from the eardrum of at least a few millimeters, preferably of at least 3 mm, more preferable of at least 10 mm, further preferred of at least 15 mm.
The tapering head portion of the otoscope for performing a method according to the present invention can be shaped with a blunt, rounded tip end, as compared to a conventionally known otoscope, thereby reducing the risk of introducing injury or discomfort to the subject. Thus, the device can be securely handled by laypersons. The otoscope adapted for performing a method according to the present invention, nevertheless, allows detecting the eardrum, since the electronic imaging unit is provided at the distal end of the head portion, exhibiting at least one optical axis which is radially offset.
Preferably, the distal end of the head portion is provided with a round and smooth shape. Moreover, the distal end may be made from a relatively soft material, such as silicone, or it may comprise an outer surface made of such a soft material. Furthermore, the longitudinal force upon introduction into the ear canal can be limited by a telescoping mechanism or the use of an elastic element. In case a telescoping mechanism is provided, preferably, the telescoping mechanism may be fixed, in order to facilitate detection of a force exerted on the otoscope.
The functional concept of a otoscope of the art as described above, however, requires the tip end of the head portion to be relatively small and acute (sharp), usually having a diameter of only about 3 mm. It is noted that the diameter of the inner part of the outer ear canal of an adult is about 4 mm. Therefore, if the user (untrained) does not pay attention, the tip portion might be introduced deeply into the inner part of the outer ear canal causing serious injuries to the subject. To substantially avoid this risk, the head portion of the otoscope adapted for carrying out a method according to the present invention (also having a tapered shape) preferably exhibits a diameter of at least 4 mm, preferably of more than 5 mm, more preferably of more than 6 mm, at a position along the longitudinal axis of the head portion of no more than 4 mm from a distal end point of the head portion. Thus, it is geometrically excluded to introduce the distal end of the head portion too far into the subject's ear canal. Different geometries of tapers may preferably be used according to the age group of the subject. For children, for example, the head portion of the otoscope adapted to carry out a method according to the present invention may exhibit a diameter of about 5 mm at a position along the longitudinal axis of the head portion of no more than 4 mm away from a distal end point of the head portion.
In a method according to the present invention, preferably, a step of relatively moving at least a portion of a probe cover covering the head portion with respect to the electronic imaging unit or the at least one optical axis is carried out, especially by a probe cover moving mechanism which is arranged for axial motion. In particular, moving the probe cover can ensure that an optical axis of the electronic imaging unit or camera can be arranged with a relatively large radial offset, especially without evoking the problem of any earwax particles obstructing visibility or with reduced probability of such earwax particles. Earwax particles or a layer of earwax often cover an inner surface of the ear canal. Thus, for an optical axis being arranged with a high radial offset, i.e. close to an inner lateral surface of the ear canal, there may be an increased likelihood of earwax particles adhering to the probe cover at a section covering the optical axis, thereby obstructing the view onto the eardrum. In other words: during insertion into the ear canal, an optical axis located radially offset at an edge of the distal tip is more likely to be obstructed by earwax. An optical axis which is radially offset is more likely to be obstructed than an optical axis which is arranged at least approximately centrically. Moving the probe cover, especially in an axial direction, can ensure that the view onto the eardrum is not obstructed, even in case the optical axis is arranged with a maximum radial offset close to an inner lateral surface of the ear canal. Thus, the present invention is based on the finding that by moving the probe cover, observation of the eardrum from an eccentric observation point with a relatively large radial offset can be made more practicable and more reliable. Moving the probe cover can ensure that the concept of “looking around the corner” is feasible and can be realized in a convenient way, even in case a layperson does not clean the ear canal prior to introduction of the head portion.
In particular, for displacing any particles or ear wax out of the line of sight, a relative motion or displacement of the probe cover induced by the moving mechanism is most effective in case the optical axis is positioned radially offset, especially with a maximum radial offset. The present invention is based on the finding that in most cases, it may be most favorable displacing the entire probe cover, apart from a central distal point at the distal tip of the probe cover. In other words: The whole probe cover can e.g. be pulled backwards in a proximal direction, except for a central distal point at the distal tip of the probe cover. At this distal point, preferably, a probe cover reservoir is provided. Thus, relative motion between the probe cover and the head portion may be minimum at the distal point, but maximum at any point of the distal tip which is positioned radially offset.
In a method according to the present invention, preferably, the probe cover is axially positioned in at least one specific axial position relative to the head portion by an adapter of the moving mechanism to which the probe cover is connected. A predefined axial position can ensure that the prove cover is moved in an axial direction only under specific conditions, e.g. when a specific (axial) force is exerted on the probe cover or the head portion, especially during insertion of the head portion into the ear canal.
In a method according to the present invention, preferably, the probe cover is axially guided along the head portion by the adapter. Axial guidance enables unfolding the probe cover such that in front of a camera, the probe cover is tensioned homogeneously.
In a method according to the present invention, preferably, during axial displacement, a reaction force is exerted on the adapter, especially in a distal axial direction, preferably by elastically deformable energy storage means. A reaction force threshold can ensure that the probe cover is only moved or displaced backwards at a time when the head portion or the distal tip of the head portion is positioned in its end position in a transition area between soft connective tissue and hard bone confining the ear canal, especially in a mechanical way.
In a method according to the present invention, preferably, the probe cover is axially displaced only if an axial force exerted on the probe cover and on the moving mechanism in the proximal direction exceeds a threshold value. A threshold value can be adjusted such that the otoscope is adapted for a specific group of persons, or for a specific kind of application. For example, the threshold value can be adjusted based on practical values, or the threshold value can be adjustable, e.g. by displacing or prestressing any energy storage means, especially elastically deformable energy storage means.
In a method according to the present invention, preferably, a displacement of the probe cover is detected by a motion sensor which is connected to the imaging unit and/or to at least one light source and/or to a logic unit of the otoscope. Detection of displacement can provide a way of coupling the displacement of the probe cover with any further method step, e.g. powering-up the camera or capturing at least one image.
In a method according to the present invention, preferably, a displacement of the probe cover is detected by the imaging unit of the otoscope. Detecting relative motion of the probe cover by the electronic imaging unit allows for control of the probe cover moving mechanism without the need of any further sensor. Controlling the step of moving the probe cover can minimize the relative motion. Preferably, the probe cover is only displaced such that an optical axis of the electronic imaging unit is not obstructed by e.g. ear wax. Friction between the probe cover and the head portion or between the probe cover and the ear canal can be minimized. Irritation of tissue can be minimized. Detection can be carried out e.g. based on transparency of the probe cover, especially in case the probe cover exhibits a varying wall thickness, or based on the color of the probe cover, especially in case the probe cover exhibits specific sections with specific colors.
In a method according to the present invention, preferably, displacement detecting by the electronic imaging unit may be combined with actuating an electromechanical latch, thus allowing for movement of the probe cover only after image analysis has revealed adequate insertion depth and/or axial or radial positioning. The electromechanical latch may be actuated only if a specific position has been detected bay the electronic imaging unit.
In a method according to the present invention, preferably, displacement of the probe cover is carried out in dependence on displacement of the electronic imaging unit or the at least one optical axis and/or the at least one light source, especially prior to any displacement of the electronic imaging unit or the at least one optical axis and/or the at least one light source. In particular, during displacement of the electronic imaging unit, images can be captured, especially continuously. Therefore, displacing the probe cover prior to any displacement of the electronic imaging unit can ensure that any potential favorable observation point is not obstructed by ear wax or other objects.
In a method according to the present invention, preferably, verifying appropriate positioning of the electronic imaging unit or the at least one optical axis is carried out based on the at least one captured image, especially during the step of introducing the electronic imaging unit, such that a user can be guided. Guidance is preferably carried out by verifying positioning based on a captured image, optionally in conjunction with data acquired by an infrared sensor unit. Guidance can facilitate use of the otoscope by laypersons. A layperson can be provided with a feedback about an appropriate insertion depth and insertion direction. Guidance can be implemented as an optical user feedback, e.g. lighted directional arrows, or as an acoustical feedback, e.g. an alerting sound, providing instructions to the user as to how to position the probe inside the ear canal.
User guidance can be carried out in conjunction with a specific method for capturing images and illuminating the ear canal. In particular, a camera or optical axis can be moved by some millimeters on a circular track while at least two light sources, especially LEDs, are alternatingly switched on. A series of images can then be captured in order to subtract artifacts, e.g. artifacts caused by dirt on a probe cover, or hairs and ear wax, and in order to discriminate the shape of the ear drum. The camera movement can be induced by a servo motor and controlled by a logic unit. According to one method, the camera is moved twice by a distance of ca. 1 mm, e.g. within ca. one second. In each of the corresponding three positions, the camera captures two images, preferably one with illumination provided by a light source arranged on one side of the camera, and one with illumination provided by a light source arranged on the other (opposed lateral) side of the camera. Both images can be averaged and subtracted, respectively. The averaged images can then be taken for calculating a final (calculated) picture through elimination of artifacts. The final picture can be freed of any (glossy) reflexes. Color information of this final picture can be evaluated, especially by quantifying the “red” components. The subtracted images measure if light reflexes vary upon changing illumination from right to left. The difference of the light reflex pattern upon switching the LEDs is very strong on a glossy surface that is near to the camera such as ear wax but weak for the ear drum reflex. This discriminates the ear drum reflex (no variation) from glossy ear wax (strong variation).
In a method according to the present invention, preferably, the user is informed by an instruction indicating an insertion depth of a handle portion of an ostoscope used for carrying out the method. Providing instructions relating to the insertion depth can reduce the risk of introducing the head portion as far as considerably within the bony part of the ear canal.
In a method according to the present invention, preferably, the user is informed by an instruction indicating a direction of rotation of a handle portion of an ostoscope used for carrying out the method. Providing instructions relating to a specific radial position or rotational position facilitates positioning of the observation point or optical axis in a favorable position with good visibility of the (entire) eardrum.
In a method according to the present invention, preferably, the user is informed by an instruction indicating a tilting angle of a handle portion of an ostoscope used for carrying out the method, especially with respect to a longitudinal axis of the ear canal. Providing instructions relating to a tilting angle can ensure that the final position of the distal tip can be found easily, eve by laypersons which are not aware of the anatomical structure of the ear canal.
In a method according to the present invention, preferably, identifying objects comprises pattern recognition of geometrical patterns, especially circular or ellipsoid shapes, or geometrical patterns characterizing the malleus bone, or further anatomical characteristics of the outer ear or the middle ear. Pattern recognition allows for more reliable identification of the eardrum. Pattern recognition can comprise recognition based on features and shapes such as the shape of e.g. the malleus, the malleus handle, the eardrum or specific portions of the eardrum such as the pars flaccida or the fibrocartilagenous ring. In particular, pattern recognition may comprise edge detection and/or spectral analysis, especially shape detection of a circular or ellipsoid shape with an angular interruption at the malleus bone or pars flaccida. Pattern recognition may be carried out in conjunction with user guidance. Especially, pattern recognition may be carried out in order to guide the user and indicate which kind of objects are observed.
In a method according to the present invention, preferably, pattern recognition is based on determination of an angle or range of angles of the objects, especially an angle with respect to an inner lateral surface of the ear canal or a longitudinal axis of the ear canal. Evaluation of the angle allows for more reliable identification of objects, especially the eardrum. Typically, the eardrum is arranged at an angle of about 30° to 60°, especially 40° to 50° with respect to an inner lateral surface of the ear canal or to a longitudinal axis of a section of the ear canal of the outer ear adjacent to the eardrum. It has been found that this anatomical characteristic can be used in order to facilitate identification of the eardrum, especially based on the assumption that any other objects within the ear canal are not arranged at any (single) specific angle. A method according to the present invention can be carried out with an otoscope comprising a logic unit which is arranged to determine the angle.
In a method according to the present invention, preferably, capturing the at least one image is carried out with the distal end, especially the distal tip, being positioned at a distance of at least 10 mm, preferably of at least 15 mm to the eardrum, especially adjacent to a curvature of the ear canal in a transition area between the two types of tissue confining the ear canal, wherein the distal end preferably is mechanically blocked and centered within the ear canal. Such a distance can ensure a good overview of the whole ear canal. Also, such a position allows for safe application of the otoscope by laypersons.
In a method according to the present invention, preferably, during introduction of the at least one optical electronic imaging unit, a force exerted on the head portion is detected, especially a force exerted in the direction of the longitudinal axis. This allows for guiding the user in dependence on the forces applied to the otoscope. Also, force detection allows for controlling a moving mechanism or a motion mechanism based on the forces applied to the otoscope, i.e. based on the position within the ear canal, e.g. relating to a situation in which the distal tip of the head portion is blocked within the ear canal, especially at an end position between the two types of tissue.
In a method according to the present invention, preferably, user guidance is carried out based on specific values of detected forces. Such a user guidance can encourage the user to further introduce the head portion, or to reduce the force exerted on the head portion. In other words: force detection can facilitate user guidance, as is can be determined if the distal tip is already positioned in an end position, or if the distal tip is not introduced deep enough yet. Also, detecting the force exerted on the probe cover or on the head portion allows for controlling or adjusting an appropriate instant of time for relatively moving the probe cover, especially automatically, such that the use of the otoscope is easy to understand for laypersons. The layperson does not have to decide whether or when the probe cover has to be moved or not.
In a method according to the present invention, preferably, forces are detected by force detection means which are coupled to a/the motion mechanism. Such force detection means allow for activating the motion mechanism in dependence on forces exerted on the head portion, especially axial forces exerted from a lateral surface of the ear canal. Such a method allows for activating the motion mechanism at a time when the distal tip of the head portion is positioned in an end position adjacent to the inner curvature of the ear canal.
Alternatively or in addition, the force detection means which are coupled to a moving mechanism for moving a probe cover arranged at the head portion, wherein the force detection means activate, especially release the moving mechanism, preferably in case a threshold value of the force is exceeded. The threshold value can be defined such that an appropriate insertion depth can be ensured. In particular, according to one preferred method, a probe cover should only be displaced at a time when the head portion is arranged at an end position. Such a threshold value, which can be defined based on e.g. experience values, ensures that the head portion is introduced deep enough. In particular, such a force detection is advantageous in context with head portions exhibiting a diameter which is larger than in prior art, in order to prevent that the head portion is introduced too deep.
In a method according to the present invention, preferably, the ear canal is illuminated by a plurality of light sources, each light source illuminating a specific section of the ear canal. Thereby, segmented lighting of the ear canal can be carried out. For example, three light sources each illuminate a specific portion of the ear canal. Feedback regulation of each of the light sources allows for homogeneous illumination of the ear canal, especially based on different illumination levels. Preferably, a logic unit is coupled to each of the light sources, the logic unit allowing for feedback regulation and/or adjustment of illumination levels.
In a method according to the present invention, preferably, the otoscope further comprises an infrared sensor unit detecting temperature of objects within the ear canal, especially of the eardrum, wherein the infrared sensor unit is positioned in the distal end, especially at the distal tip, preferably centrically at the distal tip. Detection of temperature in conjunction with capturing a plurality of images allows for reliable differentiation of objects within the ear canal.
In a method according to the present invention, preferably, identifying objects comprises identifying the eardrum, the method further comprising the step of medically characterizing the eardrum based on at least one image captured of the eardrum, in order to provide medical evidence of the eardrum. This may help the layperson to decide as to whether a physician should be visited or not.
Medically characterizing the eardrum preferably is carried out automatically by the device, especially based on predefined ranges, e.g. with respect to temperature or a specific degree of reddishness. In other words: Medically characterizing the eardrum comprises at least one step of automatically evaluating the imaged captured by the electronic imaging unit, especially by means of a logic unit, e.g. based on one of the characteristics of the eardrum described above. Thereby, pre-diagnosis may be facilitated. Any more advanced or final disease diagnosis has to be carried out by the physician on the basis of other symptoms exhibited by the subject, which are observed by the physician, or by the physician's further examination.
In a method according to the present invention, preferably, medically characterizing the eardrum includes determining the spectral composition of reflections of the eardrum, or an area around the eardrum including the eardrum. Determining the eardrum's degree of reddishness can provide an index for assessing the likelihood of inflammation of the eardrum. Inflammation of the eardrum may suggest e.g. a (bacterial/viral) infection.
In a method according to the present invention, preferably, medically characterizing the eardrum includes identifying objects within the tympanic cavity of the subject. In particular, any opaque body fluid, especially yellow body fluid, within the tympanic cavity can be evaluated as an indicator of a disease. It has been found that a relatively high intensity of illumination (transilluminating the eardrum) allows for (more reliable) acquisition of information relating to the medical condition of the patient. It has been found that any body fluid within the tympanic cavity evokes a higher degree of reflection. The fluid increases reflectance. In contrast, in case the tympanic cavity is empty, any light transilluminating the eardrum is only reflected with inferior intensity, as most of the light is absorbed within the tympanic cavity. Body fluid behind the eardrum, in particular yellow body fluid, can be evaluated as an indicator for otitis media with effusion (OME), i.e. the presence of middle ear effusion, i.e. a liquid behind the eardrum without signs or symptoms of acute infection. In particular, such body fluid can be evaluated as a precursor of an inflammation. Such body fluid may contain serous and/or mucous fluid containing white blood cells due to immune response to infection. In other words: transilluminating the eardrum and evaluating reflected light, especially in dependence on the intensity of illumination, can facilitate determining specific characteristics of the eardrum, e.g. an absolute degree of reddishness, such that the specific characteristics provide more information or more certain information with respect to the probability of any medical condition, e.g. an inflammation. This may help the layperson to decide as to whether a physician should be visited or not. Any more advanced or final disease diagnosis has to be carried out by the physician on the basis of other symptoms exhibited by the subject, which are observed by the physician, or by the physician's further examination.
In particular, the present invention is also based on the finding that the degree of reddishness of the eardrum can depend on the illumination level, i.e. the intensity of illumination. In particular, the degree of reddishness can increase with increasing intensity of illumination. The higher the intensity of illumination, the higher the degree of reddishness. Also, it has been found that at relatively high intensities of illumination, not only the eardrum, but also any other tissue can exhibit a high degree of reddishness. Therefore, observing the tympanic cavity can facilitate determining specific characteristics of the eardrum, e.g. an absolute degree of reddishness, such that the degree of reddishness provides more information or more certain information with respect to the probability of any inflammation, i.e. an inflammation index.
In a method according to the present invention, preferably, medically characterizing the eardrum includes determining a curvature, especially a convexity, of the eardrum. This allows for detecting bulging or retraction of the eardrum. This may facilitate identification of the eardrum. This may also facilitate diagnosis, as in case of body fluid within the tympanic cavity (which is an indicator for specific medical conditions), the curvature of eardrum is convex, indicating an increased pressure within the middle ear. A high amount of body fluid evokes a convex curvature, i.e. towards the otoscope. Bulging or retraction may be an indicator for a specific medical condition or disease, e.g. for OME.
In a method according to the present invention, preferably, medically characterizing the eardrum includes pressurizing the eardrum and detecting mobility of the eardrum. For example, an otoscope for carrying out the method may comprise pressurization means, e.g. a pressure transducer or a pump, configured for applying a varying pressure within the subject's external ear canal. This technique is also known as “pneumatic otoscopy”. Preferably, wherein the electronic imaging unit itself is configured for inspecting the mobility of the subject's eardrum when exposed to the varying pressure. The pressure is preferably applied by (compressed) air, wherein an air-tight chamber is formed by the subject's external ear canal and the corresponding device, i.e. the head portion or a probe cover put over the head portion.
The above mentioned object is also achieved by a method of identifying the eardrum in a subject's ear, comprising the following steps:                introducing an optical electronic imaging unit and at least one light source into an ear canal of a subject's outer ear, wherein the electronic imaging unit exhibits at least one optical axis directed in a distal direction, especially directed at the eardrum of the subject's ear;        using the electronic imaging unit to capture at least one image from at least one eccentric observation point positioned on the at least one optical axis and positioned eccentrically within the ear canal; and        determining brightness and/or color information to identify the eardrum shown in the at least one image by electronic means, in order to automatically identify the objects, especially the eardrum;the method further comprising the step of medically characterizing the eardrum based on at least one image captured of the eardrum, wherein a user guidance is carried out based on the at least one image captured of the eardrum, wherein the user is informed as how to position the electronic imaging unit in order capture the images of the eardrum, especially images of specific areas of the eardrum. Such a method may enable a layperson to apply the otoscope in order to acquire medical data of the eardrum, for facilitating a pre-diagnosis. The layperson may be guided such that the otoscope (its distal end) is positioned at a favorable observation point with respect to areas of interest of the eardrum. Any more advanced or final disease diagnosis has to be carried out by the physician on the basis of other symptoms exhibited by the subject, which are observed by the physician, or by the physician's further examination.        
Medically characterizing the eardrum may comprise diagnosing an ear disease. Such a diagnostic method may comprises all steps of the previously described inventive method of identifying objects in a subject's ear. The inventive object recognition method may form part of the inventive diagnostic method. Firstly, objects shown in the at least on captured image are identified (and distinguished from other objects in the subject's ear), and then the status (such as brightness, color, etc.) of at least one of the identified objects is determined. Such a diagnostic method may even allow for reliably diagnosing e.g. an inflammation of the eardrum without the need of assistance of a skilled physician. An otoscope adapted for carrying out the diagnostic method according to the present invention may automatically detect and identify the eardrum, medically characterize the detected eardrum, and inform the user (who may be a layperson) about a medical condition of the eardrum, e.g. whether the eardrum is inflamed or not. Such a diagnostic method may further also comprise at least some of the preferred features of the method of identifying objects in a subject's ear, as described in detail above.
For hygienic reasons, the otoscope adapted for carrying out a method according to the present invention preferably further comprises an at least partially transparent probe cover configured to be put over the head portion. The probe cover may be made from a plastic material, preferably from a transparent plastic material. Such a probe cover may be designed as a single-use product that can be produced in larger numbers with low costs. The probe cover shall be transparent, at least at the locations where it covers the electronic imaging unit, so as to allow the electronic imaging unit to have a clear view onto the eardrum. The probe cover also inhibits contamination of the head portion of the otoscope comprising the electronic imaging unit, in particular when introducing the head portion into the subject's ear canal.
Preferably, the probe cover is adapted to be fixed to at least one section of either the head portion and/or the handle portion in such a way that the probe cover does not move relative to the handle portion during displacement of the electronic imaging unit by the motion mechanism. Otherwise, artifacts, such as earwax particles, adhering to the probe cover will depicted by the electronic imaging unit, even if the electronic imaging unit is displaced by the motion mechanism. This, however, would interfere with object identification (e.g. if the object to be identified is the eardrum) and elimination of artifacts from the captured images.
The otoscope adapted for carrying out a method according to the present invention may further comprise a probe cover moving mechanism adapted to move at least a portion of the probe cover with respect to the electronic imaging unit. Thus, artifacts, such as earwax particles, adhering to the probe cover and obstructing the view of the electronic imaging unit onto the eardrum can be moved away from the electronic imaging unit by the probe cover moving mechanism. In particular, the probe cover moving mechanism can ensure that an optical axis of the electronic imaging unit or camera can be arranged with a relatively large radial offset, as mentioned above.
Preferably, the probe cover is designed in a way that allows unfolding or peeling of portions of the probe cover in order to move portions of the probe cover contaminated e.g. with earwax away from the electronic imaging unit. A method according to the present invention may further comprise a step of moving the probe cover against the electronic imaging unit or vice versa.
To illuminate the subject's ear canal and eardrum, the otoscope adapted to carry out the inventive method may further comprise at least one light source typically positioned at the distal end of the head portion, especially at the distal tip of the head portion. The term “light source” is understood to apply to any source emitting photons. A light source positioned at the distal end or tip ensures illumination of the ear canal, even in case the distal tip is only introduced as deep as a transition area between the two types of tissue. Distal light sources facilitate realization of the concept of “looking around the corner”.
Since geometrical restrictions limit the space at the distal end of the head portion, the light source is preferably formed by the distal end of a light guide. For example, the light guide may exhibit a diameter of less than 1 mm, preferably of less than 0.5 mm, more preferably of about 0.2 mm. The light guide may be connected to an LED located remote from the distal end of the head portion. The light guide may be e.g. a nylon light guide, preferably having a diameter of only about 0.2 mm to 1 mm. Alternatively, a light source may be formed e.g. by a small light emitting diode (LED) that is placed directly at the distal end of the head portion. The LED can ensure illumination with low energy consumption and minimum generation of heat.
The light guide can be made of polymethyl methacrylate (PMMA) or polyamide, especially polyamide 6.6. PMMA provides the advantage of good optical characteristics. Polyamide 6.6 provides the advantage of high flexibility.
It is advantageous, if the otoscope adapted to carry out the inventive method comprises a plurality of light sources at the distal end of the head portion, preferably with each light source being separately controllable. Thereby, the ear canal can be illuminated from a favorable eccentric illumination point, reducing e.g. shadowing. Also, by illuminating objects in the subject's ear canal from different positions, e.g. by sequentially switching on and off the individual light sources, it may also be envisaged to distinguish different objects in the ear, without necessarily having to displace the electronic imaging unit by a motion mechanism within the ear canal. An object relatively far away from the electronic imaging unit, such as the eardrum, will change its appearance only slightly when being illuminated from different positions at the distal end of the head portion. However, artifacts that are relatively close to the electronic imaging unit (such as hair and earwax) will change their appearance (position) drastically. The otoscope therefore preferably comprises means, in particular a logic unit, such as a microprocessor, adapted to distinguish different objects in the subject's ear based on images taken with the objects being illuminated from different positions.
Additionally or alternatively, the at least one light source may be controlled in view of the color, so that the color of the light emitted by the light source is changed. For example green color may be preferred to recognize earwax.
Preferably, a logic unit is coupled with at least two of the light sources and is arranged for individually switching on and off the light sources and/or for individually varying the light intensity. Preferably, the otoscope comprises the logic unit. The logic unit allows for feedback regulation and/or adjustment of illumination levels. Individually switching on and off enables stereoscopic viewing, especially depth analysis along the optical axes due to changes in reflected light patterns. Also, segmented lighting of the ear canal can be carried out. For example, three light sources each illuminate a specific portion of the ear canal. Feedback regulation of each of the light sources allows for homogeneous illumination of the ear canal, especially based on different illumination levels. Varying and adjusting the illumination level facilitates identification of the eardrum, in particular in dependence on the spectral composition of reflections of the eardrum with respect to surrounding tissue and with respect to a specific intensity of illumination. Preferably, the logic unit comprises at least one dimmer switch. Preferably, the least one light source preferably is dimmable, especially continuously dimmable.
Like the electronic imaging unit, the at least one light source is preferably positioned radially offset from the longitudinal axis of the head portion. Such a configuration allows illumination of the eardrum without the need to introduce the light source as deeply into the ear canal as it would be necessary, if the light source were placed centrally on the longitudinal axis of the head portion. The offset may be at least 1 mm, preferably at least 1.5 mm, more preferably at least 2 mm from the longitudinal axis. Preferably, the offset is maximum with respect to the confines of the outer diameter of the head portion. According to one embodiment, the offset is in the same range as a radial offset of the at least one optical axis. According to one embodiment, the radial offset of the at least one light source is as large as a radial offset of a camera of the electronic imaging unit. Such an arrangement is favorable in order to observe the entire eardrum or in order to reduce shadowing.
Preferably, the at least one light source is positioned adjacent to the at least one optical axis, preferably in a distance (b) smaller than 2 mm, more preferable smaller than 1.5 mm, further preferable smaller than 1.3 mm, especially between 1 mm and 1.3 mm or between 0.6 mm and 0.8 mm. Such an arrangement can enable emission of light with respect to one specific camera or optical axis. In particular, shadowing can be reduced. Light can be emitted onto the eardrum from a favorable position, especially e.g. in a direction which is at least approximately parallel to the ear canal. Also, an arrangement close to the optical axis can ensure that the light source can easily be displaced in conjunction with the optical axis in order to position the light source at a favorable eccentric illumination point.
Preferably, the otoscope exhibits at least two light sources or light guides which are arranged in a maximum distance (d) apart from each other, wherein the maximum distance (d) is at least 3.5 mm, more preferable at least 4 mm, further preferred in a range between 4.2 mm and 4.6 mm. Such an arrangement is favorable in order to observe the entire eardrum, especially without the need of rotating the camera or light source in a specific position. The relatively large distance can ensure that it is likely that one of the at least two, three or four light sources is arranged in a favorable eccentric illumination point.
Preferably, the at least one light source is arranged so as to maintain a predetermined distance with respect to the electronic imaging unit, even when the electronic imaging unit is displaced by the motion mechanism. Such a configuration is advantageous, because the predetermined distal relationship between the at least one light source and the electronic imaging unit allows for improved (automatic) image analysis. If a motion mechanism is provided, the motion mechanism preferably also displaces the at least one light source. If the light source is provided in the form of a light guide, the light guide should be sufficiently flexible to allow for such a displacement of the at least one light source. Preferably, the light guide is fixed distally within the head portion, wherein the light guide is elastic, the elasticity allowing for bending and/or twisting. Alternatively, the light guide may be rigid, wherein the entire lightning apparatus may be displaced in conjunction with the head portion.
Preferably, the at least one light source is coupled with the motion mechanism, especially directly or via the electronic imaging unit, such that the motion mechanism allows for at least partial rotation of the at least one light source about an axis of rotation, wherein the axis of rotation preferably corresponds to the longitudinal axis. Rotating the light source in a favorable position can allow for observing the entire eardrum with a high reliability.
Preferably, the at least one light source is fixed at the electronic imaging unit, in particular laterally fixed at a camera of the electronic imaging unit or at a support accommodating at least one optical component of the electronic imaging unit or defining the least one optical axis. With such an arrangement, rotation of both the electronic imaging unit and the light source can be realized quite easily. Thereby, the motion mechanism only has to be coupled with one of these components.
Preferably, the otoscope further comprises an infrared sensor unit positioned at the distal end of the head portion, especially centrically at the distal tip. Providing an otoscope comprising an infrared sensor unit for temperature detection in conjunction with an optical identification of objects allows for more reliable identification of the objects, e.g. of the eardrum.
The otoscope adapted for carrying out the inventive method may further comprise a logic unit, such as a microprocessor. The logic unit may be adapted to control the electronic imaging unit and/or the at least one light source and/or an infrared sensor unit. The logic unit may analyze the images obtained by the electronic imaging unit e.g. in order to compare two images obtained with the electronic imaging unit located at different positions within the ear and/or with the object illuminated from different positions, so as to identify and discriminate different objects in the subject's ear. The logic unit may further be adapted to generate or calculate a new image wherein predetermined objects that have been previously identified are eliminated.
In case any reference sign is not explicitly described in a respective figure, it is referred to the other figures. In other words: Like reference characters refer to the same parts or the same type or group of device throughout the different views.